Involvement of the prostate and testis expression (PATE)-like proteins in sperm-oocyte interaction

Area of Science:

• Reproductive Biology
• Spermatogenesis
• Male Reproductive System

Background:

• Prostate and testis expression (PATE)-like proteins are primarily found in the male reproductive tract.
• These proteins are homologous to SP-10 (ACRV1), an acrosomal vesicle protein, and are located in the sperm head.

Purpose of the Study:

• To investigate the expression and functional significance of three PATE-like proteins in human testes and ejaculated sperm.
• To determine the role of PATE protein in sperm function, specifically sperm-zona binding and sperm-oolemma fusion.

Main Methods:

• Human testis biopsies (n=95) and sperm cells were analyzed using RT-PCR, immunohistochemistry, and immunofluorescence staining.
• Sperm function was assessed via the hemizona assay and hamster egg penetration test (HEPT) using an antibody against PATE protein.

Main Results:

• PATE and PATE-M proteins were predominantly found in germ cells (85% and 50% positive, respectively), localized to the sperm head's equatorial segment.
• PATE-B was found in 2% of germ cells, localized to the post-acrosomal region.
• PATE antibody did not affect sperm-zona binding but significantly inhibited sperm-oolemma fusion and penetration in the HEPT (P < 0.001).

Conclusions:

• PATE protein plays a crucial role in the sperm-oolemma fusion process during fertilization.
• The findings indicate PATE protein is essential for sperm penetration into the egg but not for binding to the zona pellucida.